8.2. Bacterial Diversity in The Nitrogen Cycle

Question 1

Microorganisms can use nitrogen in 3 forms:

Answer 1

1. ammonia/ ammonium (NH3/ NH4+)
2. Nitrate/ Nitrite (NO3-/NO2-)
3. dinitrogen (N2)

Question 2

T/F

All life forms must assimilate nitrogen, and nitrogen must be transformed to be assimilated into the organism

Answer 2

true

Question 3

T/F

Archaea are the only life forms that can conserve energy from transformations of inorganic nitrogen species

Answer 3

False

Archaea AND BACTERIA are the only ones

Question 4

What are the 3 broad groups of bacteria/ archaea that control the nitrogen cycle?

Answer 4

1. Diazotrophs
2. Nitrifiers
3. Denitrifiers

Question 5

Diazotrophs (aka _____-fixing bacteria) fix ___ to make ___

Answer 5

Nitrogen (N2)

N2 –> NH3

Question 6

____ is the only biologically available form of nitrogen

Answer 6

NH3
(incorporated into amino acids)

Question 7

T/F

N2 fixation is relatively energy inexpensive

Answer 7

False
very energy EXPENSIVE
- it’s a huge investment to make N2 into biologically available NH3

Question 8

Nitrogenase=

Answer 8

the enzyme that completes nitrogen fixation (O2 sensitive)

Question 9

Many diazotrophs evolved the ability to protect nitrogenase from ___

Answer 9

oxygen

Question 10

T/F

LUCA was an N2 fixator

Answer 10

We don’t know

Originally thought this was true, now we’re not sure